1. Technical Field
This invention relates in general to an improved hard disk drive and in particular to altering the internal pressure of a disk drive to improve its performance. Still more particularly, the invention relates to a system and method for calibrating and controlling the internal pressure of a disk drive.
2. Description of the Prior Art
Generally, a digital data access and storage system consists of one or more storage devices that store data on storage media such as magnetic or optical data storage disks. In magnetic disk storage systems, a storage device is called a hard disk drive (HDD), which includes one or more hard disks and an HDD controller to manage local operations concerning the disks. Hard disks are rigid platters, typically made of aluminum alloy or a mixture of glass and ceramic, covered with a magnetic coating. Typically, two or three platters are stacked vertically on a common spindle that is turned by a disk drive motor at several thousand revolutions per minute (rpm).
The only other moving part within a typical HDD is the head assembly. Within most drives, one read/write head is associated with each side of each platter and flies just above or below the platter""s surface. Each read/write head is connected to a semi-rigid arm apparatus which supports the entire head flying unit. More than one of such arms may be utilized together to form a single armature unit.
Each read/write head scans the hard disk platter surface during a xe2x80x9creadxe2x80x9d or xe2x80x9cwritexe2x80x9d operation. The head/arm assembly is moved utilizing an actuator which is often a voice coil motor (VCM). The stator of a VCM is mounted to a base plate or casting on which is also mounted the spindle supporting the disks. The base casting is in turn mounted to a frame via a compliant suspension. When current is fed to the motor, the VCM develops force or torque which is substantially proportional to the applied current. The arm acceleration is therefore substantially proportional to the magnitude of the current. As the read/write head nears the desired track, a reverse polarity signal is applied to the actuator, causing the signal to act as a brake, and ideally causing the read/write head to stop directly over the desired track.
In the prior art, the individual enclosures or housings used to support the disk drive assemblies are typically unsealed and expose the drive components to the ambient atmospheric conditions of the surrounding environment (e.g., temperature and pressure) where the host computer system is located. Although the ambient conditions are usually sufficient to provide an adequate operational environment for most disk drives, they may be less than ideal for optimal performance under all types of operating requirements. Thus, a disk drive that is capable of enhancing its internal environmental conditions would be desirable.
A sealed computer disk drive contains a vacuum pump for decreasing the internal pressure inside the drive. The lower internal operating pressure decreases aerodynamic drag between the actuator arm assemblies and the rotating disks. In addition, the power consumed by the drive is reduced and the its operating temperature is lowered. The fly height of the heads relative to the disks or the head-disk interface condition is also monitored. The pump is selectively actuated in response to the measured change in flying height of the heads from their original manufactured settings. In one version, the drive is also equipped with a pressure transducer for monitoring the drives internal pressure.
Accordingly, it is an object of the invention to provide an improved computer hard disk drive.
It is an additional object of the invention to alter the internal operating pressure of a disk drive to improve its performance.
Still another object of the invention is to provide a system and method for calibrating and controlling the internal operating pressure of a disk drive.
The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the preferred embodiment of the present invention, taken in conjunction with the appended claims and the accompanying drawings.